Reformable Resin Filaments and Materials Formed Therewith

ABSTRACT

The present teachings contemplate forming a reformable epoxy resin material into a monofilament having a denier of from about 50 to about 5000 and a glass transition temperature of less than about 200° C.; loading one or more monofilaments onto a spool; co-weaving the one or more monofilaments with a reinforcing fiber to form a woven material, the reinforcing fiber having a glass transition temperature of greater than 200° C.; heating the woven material to form a composite to a temperature so that only the one or more monofilaments soften but the reinforcing fiber does not.

TECHNICAL FIELD

The present invention pertains generally to reformable epoxy resins foruse in monofilament fibers, and more particularly to drapable materialsformed using said fibers and composite structures formed therewith.

BACKGROUND

Industrial fiber materials often require means to hold or bind materialstogether. Often, thermoplastic materials (e.g., fibers) are used tostitch or bind the materials together. However, such current methodsinclude a number of drawbacks including but not limited to theincompatibility of typical thermoplastics with secondary materials (inparticular epoxy-based composite materials), lack of sufficientblending, yarn showing through composite surfaces, behavior ofthermoplastics upon sanding or cutting of secondary materials, rigidityof typical thermoplastics and lack of reformability of typicalthermoplastics.

Reformable thermoplastic polymers having at least one epoxide group havebeen described in U.S. Pat. Nos. 5,115,075; 4,438,254; 6,011,111; and WO98/14498 (see e.g., pages 3-8) along with illustrative synthesisconditions, all incorporated by reference herein (see also U.S. Pat.Nos. 3,317,471 and 4,647,648, also incorporated by reference herein).Examples of such materials (e.g., reformable resin materials) also canbe found, without limitation at paragraphs 15-25 of Published U.S.Patent Application No. 20070270515 (Chmielewski et al), incorporated byreference for all purposes.

The use of such thermoplastic polymers in a composite material has beendisclosed in PCT Publication number WO/2008/010823 (addressing in situreaction of an epoxy and an amine after impregnation), incorporated byreference herein.

Yarns utilizing these reformable epoxy resin materials have beendisclosed in PCT publication number WO2016/065104. However, thisdisclosure fails to identify monofilaments having the required denierfor use on the composite structures described herein.

There is thus a need for materials that have certain thermoplasticcapabilities and desirable small denier in a single monofilament in thatthey can be woven with fibers having much higher glass transition topromote constant thickness of a composite structure formed by the wovenmaterial.

SUMMARY OF THE INVENTION

The teachings herein are directed to a method comprising forming areformable epoxy resin material into a monofilament having a denier offrom about 50 to about 1000 and a glass transition temperature of lessthan about 200° C., loading one or more monofilaments onto a spool,co-weaving the monofilaments with a reinforcing fiber to form a wovenmaterial, the reinforcing fiber having a glass transition temperature ofgreater than 200° C., heating the woven material to form a composite toa temperature so that only the one or more monofilaments soften but thereinforcing fiber does not.

The reinforcing fiber may be selected from the group consisting of glassfibers, carbon fibers, aramid fibers, polymer fibers (e.g.,polyethylene, polypropylene, polyamide, polyester) and combinationsthereof. The resulting composite may have a constant thickness as aresult of the failure of the structural fibers to soften. The resultingcomposite may be utilized to form an armor material (e.g., a compositearmor material or a composite ballistic armor material). The resultingcomposite may be used to form a helmet, a jacket, a shield or the like.One or more of the denier or diameter of the monofilament may besubstantially similar to that of the reinforcing fiber. One or more ofthe denier or diameter of the monofilament may be less than that of thereinforcing fiber. One or more of the denier or diameter of themonofilament may be greater than that of the reinforcing fiber. Theresulting composite may be an epoxy laminate. The resulting compositemay be substantially free of any film layer.

The method may be substantially free of surface treatment for formingclass A surfaces. The resulting composite may be paintable. Themonofilament may develop adhesive properties upon softening. The shelflife of the monofilament may be at least about 3 months, at least about6 months, at least about 1 year, or even at least about 5 years. Themonofilament may be recyclable. The resulting composite may be drapable.

The teachings herein are also directed to a monofilament having a denierof from about 5 to 5000, or from about 200 to 3200 and a glasstransition temperature of less than about 200° C. and comprising areformable epoxy resin material. The reformable epoxy resin material maybe formed as a reaction product of a difunctional epoxy resin and aprimary amine. The reformable epoxy resin material may be formed as areaction product of bisphenol A diglycidyl ether (BADGE) andmonoethanolamine. The monofilament may be drapable. The monofilament maybe woven to form an end product that is drapable.

The teachings herein are further directed to a fibrous material productformed from the monofilament described herein woven with one or morereinforcing fibers having a glass transition temperature of 200° C. orgreater. The fibrous material product may be drapable.

Also, envisioned are ballistic composite materials including one or morelayers comprising a woven material formed from a plurality of reformableepoxy resin monofilaments and a plurality of reinforcing fibers. Thecomposite material may be used to form a helmet. The composite materialmay be used to form body armor. The composite material may be used toform a shield. The composite material may be formed in a heated press ata temperature below about 200° C.

The teachings herein provide for a reformable resin monofilament havinga particular denier and glass transition temperature so that it can bewoven with a reinforcing fiber to form a composite having asubstantially constant thickness after exposure to heat for forming thecomposite.

DETAILED DESCRIPTION

The present teachings meet one or more of the above needs by theimproved composite structures and methods described herein. Theexplanations and illustrations presented herein are intended to acquaintothers skilled in the art with the teachings, its principles, and itspractical application. Those skilled in the art may adapt and apply theteachings in its numerous forms, as may be best suited to therequirements of a particular use. Accordingly, the specific embodimentsof the present teachings as set forth are not intended as beingexhaustive or limiting of the teachings. The scope of the teachingsshould, therefore, be determined not with reference to the abovedescription, but should instead be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. The disclosures of all articles and references,including patent applications and publications, are incorporated byreference for all purposes. Other combinations are also possible as willbe gleaned from the following claims, which are also hereby incorporatedby reference into this written description.

This application is related to and claims the benefit of the filing dateof U.S. Provisional Application Ser. No. 62/683,229, filed Jun. 11,2018, the contents of that application being hereby incorporated byreference herein for all purposes.

The teachings herein make advantageous use of a reformable epoxyfilament (e.g., monofilament) that adheres when cooled. The teachingsherein contemplate a method for providing composite structures or othermolded structures that are assembled (e.g., stitched, woven or formedwith a web or mesh) with the filaments (e.g., weavable reformable epoxyresin filaments) described herein. The resulting structures are formableand moldable after the reformable epoxy monofilament is heated andsubsequently falls below its glass transition temperature. Thereformable epoxy filaments are particularly compatible with dissimilarreinforcing fibers and epoxy based secondary materials such that thecompatibility is improved over typical thermoplastic fibers (e.g.,polyester). The glass transition temperature of the reinforcing fibersmay be higher than that of the reformable epoxy filaments may be heatedmay be heated and softened while the reinforcing fibers do not soften.

The teachings herein provide for a number of uses for the reformableepoxy monofilaments. In one embodiment, the reformable epoxy filamentsmay be woven with reinforcing fibers. Examples of which include but arenot limited to glass, carbon, aramid, and/or polyamide fibers. Thereformable epoxy filaments may be more compatible with the reinforcingfibers as compared to typical thermoplastic fibers. This may be due tothe similarity in size, diameter and/or denier of the reformable epoxyfilaments and reinforcing fibers. For example, the reformable epoxymonofilaments may have a denier of from about 5 to about 6000, fromabout 30 to about 4000, from about 175 to about 3800, or even from about200 to about 3200. The reformable epoxy monofilaments may have a denierof from about 100 to about 1000, from about 150 to about 500, or evenfrom about 200 to about 400. Upon weaving the reformable epoxymonofilaments with a reinforcing fiber, these woven structures fiberscan be used to produce drapable materials and composites that maintaindesired consistent thickness, strength and adhesion. The flexible natureof the resulting structures are easier to form than rigid composites,enable more complex shapes, require less heat/energy to process, and hasa higher modulus than typical thermoplastic fibers.

In another embodiment, the reformable epoxy filament may be combinedwith additional monofilaments to a desired thickness and those combinedfilaments may be woven with a reinforcing fiber. This allows forspecific customization of the size of the reformable epoxy material sothat the epoxy filaments are compatible with a selected reinforcingfiber.

The materials and methods taught herein include possible uses forreformable epoxy filaments. It is possible that the reformable epoxymaterials may be provided initially in a pellet form and then formedinto a spooled filament. The spooled filament and a spooled reinforcingfiber may be located adjacent one another for simplified weaving.

The reformable epoxy monofilaments described herein may be utilized toform composite structures that can be molded to form helmets, bodyarmor, shields, or protective armor (e.g., a composite armor material ora composite ballistic armor material) of any kind. It is desirable thatthese composites (or the layer of the composite formed with thereformable epoxy monofilaments) have a consistent cross section and/orthickness. This is made possible by weaving the filaments with areinforcing fiber, whereby when exposed to elevated temperatures, thereformable epoxy filaments soften and adhere and the reinforcing fibersdo not soften and are thus capable of maintaining the desired consistentcross section and/or thickness.

The processing temperature may affect the yarn formation process in thatthe viscosity of the reformable epoxy materials my require adjustment toform the desired monofilaments. Specifically, the materials may requireprocessing at a temperature of at least 150° C., at least 170° C., atleast 190° C. or even at least about 200° C. At lower processingtemperatures the viscosity of the materials may be too high forformation into monofilaments. In one embodiment it is possible that thematerial is formulated to have a lower viscosity (sufficient for forminginto filaments) even at temperatures below 200° C., below 170° C., oreven below 150° C. However, the temperature for processing thereformable epoxy materials may continue to be below that of thetemperature required to process fibers formed of other materials such astypical thermoplastics. The use of lower processing temperatures reducesthe risk of thermal stability of the filaments during processing andalso allows for easier cooling of the filaments. Cooled filamentsminimize any unwanted fiber tackiness so that the filaments are notsticky when wound.

A key advantage of the present teachings over existing commonly usedfibers (e.g., polyester fibers) is the improved compatibility with othermaterials including epoxy-based thermoset epoxy resin matrix materials(commonly utilized in composite structures). Specifically, thereformable monofilament may be an amine terminated resin that canpotentially react with a thermoset resin. Further, the low glasstransition temperature of the filaments described herein are beneficialin that the disclosed filaments can be easily softened at a lowtemperature without softening the reinforcing fibers woven with thereformable epoxy filaments. Additional benefits of the reformable epoxyfilaments include fast adhesion, and also the ability to re-form andre-mold the filaments with the addition of heat. Adhesion and returningto a solid state upon cooling of the reformable epoxy filaments beginsalmost immediately after heating is stopped and full adhesion can occurwithin about 10 seconds to about 60 seconds (e.g., about 30 seconds). Inaddition, a reformable epoxy filaments may be desirable because of itslong shelf life. It also may not require storage at a refrigeratedtemperature, unlike some alternative materials.

As an example, the reformable epoxy material for forming the filamentsmay be and/or may include a product (e.g., a thermoplastic condensationreaction product) of a reaction of a mono-functional or di-functionalspecies (i.e., respectively, a species having one or two reactivegroups, such as an amide containing species), with an epoxide-containingmoiety, such as a diepoxide (i.e., a compound having two epoxidefunctionalities), reacted under conditions for causing the hydroxylmoieties to react with the epoxy moieties to form a generally linearbackbone polymer chain with ether linkages. Exemplary reformable epoxymaterials may be made with a difunctional epoxy resin and a primaryamine which may be bisphenol A diglycidyl ether (BADGE) andmonoethanolamine. For some applications that may require a higher glasstransition temperature (T_(g)), it is contemplated that BADGE may bereplaced by an epoxy monomer with less mobility. Such epoxy monomers mayinclude diglycidylether of fluoren diphenol or 1,6 napthalene diepoxy.Also, it is contemplated that where fire resistance is desired, BADGEcan be replaced by a brominated bisphenol A epoxy resin. Alternatively,the reformable epoxy materials disclosed herein may also be known aspoly(hydroxyamino ether) (PHAE) as illustrated in U.S. Pat. Nos.5,164,472; 5,275,853; 5,401,814 and 5,464,924, all incorporated byreference herein for all purposes. Such polyethers may be prepared byreacting a diglycidyl ether of dihydric aromatic compounds such as thediglycidyl ether of bisphenol A, or a diepoxy-functionalizedpoly(alkylene oxide) or mixture thereof with a primary amine or asecondary diamine or a monoamine functionalized poly(alkylene oxide) ormixture thereof. Such material generally has a relatively high flexuralstrength and modulus—often much higher than typical polyolefins (i.e.polyethylene and polypropylene)—and has the added benefit of being meltprocessable at temperatures of 150 to 200° C. Though otherepoxide-containing moieties may be employed, as is taught in U.S. Pat.No. 6,011,111 (incorporated by reference; see, e.g., Cols. 5-6), and WO98/14498 (incorporated by reference; see, e.g., page 8) such moietiesmay include at least one mono-functional epoxide and/or a di-functionalepoxide (“diepoxide”). An example of a diepoxide that can be employed inthe teachings includes a diglycidyl ether of a dihydric phenol (e.g.,resorcinol, biphenol or bisphenol A). Any epoxide-containing moietyherein may be an aliphatic and/or an aromatic epoxide.

Other examples of illustrative materials, functional species anddiepoxides are described in U.S. Pat. Nos. 5,115,075; 4,438,254; and WO98/14498 (see e.g., pages 3-8) along with illustrative synthesisconditions, all incorporated by reference herein (see also U.S. Pat.Nos. 3,317,471 and 4,647,648, also incorporated by reference herein).Examples of such materials also can be found, without limitation atparagraphs 15-25 of Published U.S. Patent Application No. 20070270515(Chmielewski et al), incorporated by reference for all purposes.

Forming the reformable epoxy materials into the desired monofilamentformat may require particularly high temperatures during the extrusionprocess. Accordingly, it may be necessary to reduce the viscosity of theRER as the heat tends to increase the viscosity to an undesirable range.This may be achieved by modifying the ratio of the difunctional epoxyresin and primary amine such that the molecular chain length is reducedthus reducing the viscosity.

As used herein, unless otherwise stated, the teachings envision that anymember of a genus (list) may be excluded from the genus; and/or anymember of a Markush grouping may be excluded from the grouping.

Unless otherwise stated, any numerical values recited herein include allvalues from the lower value to the upper value in increments of one unitprovided that there is a separation of at least 2 units between anylower value and any higher value. As an example, if it is stated thatthe amount of a component, a property, or a value of a process variablesuch as, for example, temperature, pressure, time and the like is, forexample, from 1 to 90, preferably from 20 to 80, more preferably from 30to 70, it is intended that intermediate range values such as (forexample, 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc.) are within theteachings of this specification. Likewise, individual intermediatevalues are also within the present teachings. For values which are lessthan one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 asappropriate. These are only examples of what is specifically intendedand all possible combinations of numerical values between the lowestvalue and the highest value enumerated are to be considered to beexpressly stated in this application in a similar manner. As can beseen, the teaching of amounts expressed as “parts by weight” herein alsocontemplates the same ranges expressed in terms of percent by weight.Thus, an expression in the of a range in terms of at “‘x’ parts byweight of the resulting polymeric blend composition” also contemplates ateaching of ranges of same recited amount of “x” in percent by weight ofthe resulting polymeric blend composition.”

Unless otherwise stated, all ranges include both endpoints and allnumbers between the endpoints. The use of “about” or “approximately” inconnection with a range applies to both ends of the range. Thus, “about20 to 30” is intended to cover “about 20 to about 30”, inclusive of atleast the specified endpoints.

The disclosures of all articles and references, including patentapplications and publications, are incorporated by reference for ailpurposes. The term “consisting essentially of to describe a combinationshall include the elements, ingredients, components or steps identified,and such other elements ingredients, components or steps that do notmaterially affect the basic and novel characteristics of thecombination. The use of the terms “comprising” or “including” todescribe combinations of elements, ingredients, components or stepsherein also contemplates embodiments that consist of, or consistessentially of the elements, ingredients, components or steps.

Plural elements, ingredients, components or steps can be provided by asingle integrated element, ingredient, component or step. Alternatively,a single integrated element, ingredient, component or step might bedivided into separate plural elements, ingredients, components or steps.The disclosure of “a” or “one” to describe an element, ingredient,component or step is not intended to foreclose additional elements,ingredients, components or steps.

It is understood that the above description is intended to beillustrative and not restrictive. Many embodiments as well as manyapplications besides the examples provided will be apparent to those ofskill in the art upon reading the above description. The scope of theinvention should, therefore, be determined not with reference to theabove description, but should instead be determined with reference tothe appended claims, along with the full scope of equivalents to whichsuch claims are entitled. The disclosures of all articles andreferences, including patent applications and publications, areincorporated by reference for all purposes. The omission in thefollowing claims of any aspect of subject matter that is disclosedherein is not a disclaimer of such subject matter, nor should it beregarded that the inventors did not consider such subject matter to bepart of the disclosed inventive subject matter.

1. A method comprising: i) forming the monofilament of claim 17; ii)loading one or more of the monofilaments onto a spool; iii) co-weavingthe one or more monofilaments with a reinforcing fiber to form a wovenmaterial, the reinforcing fiber having a glass transition temperature ofgreater than 200° C.; iv) heating the woven material to form a compositeto a temperature so that only the one or more monofilaments softens butthe reinforcing fiber does not.
 2. The method according to claim 1,wherein the reinforcing fiber is selected from the group consisting ofglass fibers, carbon fibers, aramid fibers, polymer fibers(polyethylene, polypropylene, polyamide, polyester), metallic fibers,and combinations thereof.
 3. The method according to claim 1, whereinthe resulting composite has a constant thickness as a result of thefailure of the structural fibers to soften. 4-5. (canceled)
 6. Themethod according to claim 1, wherein one or more of the denier ordiameter of the monofilament is substantially similar to that of thereinforcing fiber.
 7. The method according to claim 1, wherein one ormore of the denier or diameter of the monofilament is less than that ofthe reinforcing fiber.
 8. (canceled)
 9. The method according to claim 1,wherein the resulting composite is an epoxy laminate.
 10. The fibrousmaterial product according to claim 22, wherein the resulting compositeis substantially free of any film layer. 11-12. (canceled)
 13. Thefibrous material product of claim 22, wherein the monofilament developsadhesive properties upon softening.
 14. (canceled)
 15. The monofilamentaccording to claim 17, wherein the monofilament is recyclable. 16.(canceled)
 17. A monofilament having a denier of from about 200-3200 anda glass transition temperature of less than about 200° C. and comprisinga reformable epoxy resin material.
 18. The monofilament of claim 17,wherein the reformable epoxy resin material is formed as a reactionproduct of a difunctional epoxy resin and a primary amine.
 19. Themonofilament of claim 17, wherein the reformable epoxy resin material isformed as a reaction product of bisphenol A diglycidyl ether (BADGE) andmonoethanolamine.
 20. The monofilament of claim 17, wherein themonofilament is drapable.
 21. The monofilament of claim 17, wherein themonofilament is woven to form an end product that is drapable.
 22. Afibrous material product formed from the monofilament of claim 17 wovenwith one or more reinforcing fibers the one or more reinforcing fibershaving a glass transition temperature of 200° C. or greater.
 23. Thefibrous material product of claim 22, wherein the product is drapable.24. A ballistic composite material including one or more layerscomprising a woven material formed from a plurality of the reformableepoxy resin monofilaments of claim 17 and a plurality of reinforcingfibers.
 25. The composite material of claim 24, wherein the material isused to form a helmet, body armor, or a shield. 26-27. (canceled) 28.The composite material of claim 24, wherein the composite is formed in aheated press at a temperature below about 200° C.
 29. The compositematerial of claim 24, wherein the reinforcing fibers are selected fromglass fibers, carbon fibers, aramid fibers, polymer fibers(polyethylene, polypropylene, polyamide, polyester), metallic fibers,and combinations thereof.